Archive - Spicebush Swallowtail and Pipevine Swallowtail Butterflies
September 17, 2025
This EPOD was originally published September 18, 2010
Photographer: Don G. Lambert
Summary Author: Don G. Lambert 
The photo pair above shows a spicebush swallowtail (Papilio troilus) at left and a pipevine swallowtail (Battus philenor) butterfly at right. Note that the orange dots on the undersides of the hind wings are very different in these two species. Spicebush swallowtails mimic pipevines. The underside of the pipevine is mostly brownish-black with an inverted C in orange spots. When the wings are at a certain angle to the Sun, a brilliant iridescent blue appears, apparently caused by cell structures which act as a diffraction grating. The function of this iridescence has been thought to be to attract a mate or to warn predators of the pipevine's poisonous nature. The larvae feed on the pipevine bush, which contains poisonous compounds such as aristolochic acid. Like the monarch butterfly, whose larvae ingest poisons from milkweed, the adults retain the poisons. In addition to the spicebush swallowtail, pipevine swallowtails are mimicked by other nonpoisonous species such as the eastern tiger swallowtail. Photo taken on August 8. 2010.
Photo Details: Both images taken with a Canon EOS Rebel T1 camera with an 18-200 mm Canon lens in a field near my home. Left photo taken 8/7/2010 at 8:41 a.m -- f 7.1; 1/250 seconds; ISO 100; 200 mm. Right photo taken 8/8/2010 at 11:39 a.m. -- f 5.7; 1/1600 second; ISO 640; 200 mm. Thanks to Monika Landy-Gyebnar, Jeff Pippen and Bill Hilton for their help.
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